Biochar filter: use of biochar in agriculture as soil conditioner Report for BSAS Commitment 2010 Photo: Jarkko Hovi Tero Brandstaka1, Juha Helenius1, Jarkko Hovi1, Jukka Kivelä1, Kari Koppelmäki2, Asko Simojoki3, Helena Soinne4 & Priit Tammeorg1 1University of Helsinki Department of Agricultural Sciences, 2Uusimaa Centre for Economic Development, Transport and the Environment, 3University of Helsinki Department of Food and Environmental Sciences, 4MTT Agrifood Research Finland University of Helsinki, December 2010 This report is for use of the Baltic Sea Action Summit (BSAS) Helsinki 2010 community http://www.bsas.fi/commitments/all-commitments/biochar-filter-research-on-using-biochar- mixed-soil-in-filtering-impurities-from-water-running-from-agricultural-lands-to-the-baltic- sea Recommended citation : Brandstaka, T., J. Helenius, J. Hovi, J. Kivelä, K. Koppelmäki, A. Simojoki, H. Soinne & P. Tammeorg 2010. Biochar filter: use of biochar in agriculture as soil conditioner. Report for BSAS Commitment 2010, 22 pp. December 2010, unpublished. 2 Abstract Biochar is material produced via pyrolysis of biomass feedstocks. It is a mixture of char and ash, but it is mainly (70 - 95%) carbon (C). Potential for production of significant amounts of biochar exist, as pyrolysis based technologies are being developed for energy industry and for production of wide variety of chemicals from forest feedstocks. Potential benefits listed in literature include carbon sequestration by the natural process of photosynthesis, reduction of N2O- ja CH4 -emissions from soils, net production of energy in form of bioenergy, increase in soil fertility and yields of agricultural crops, increase in microbial activity in the soil, improvement of water retention capacity in the soil, improvement of cation exchange capacity in the soil, improvement of durability of soil aggregates and reduction of erosion, reduction in need of fertilization, and reduction of nutrient leaching. The aims of this study were to test effects of biochar as soil conditioner to soil properties, and to yield and quality of a range of agricultural crops. Direct measurements of impact on nutrient loading were not aimed at. Indirect evidence, through impacts in soil and to yields was seeked for. These include effects on soil aggregate stability, liming effect, water retention, and nutrient use efficiency of agricultural crops. Demonstration in a farmer’s field aimed at getting experience on applicability of biochar in real farming conditions. The biochar material was carbonized from spruce chips in 500 to 550 oC in an experimental plant in Finland. Its chemical composition, its liming effect, its effect on soil aggregate stability, and its effect on soil moisture were studied. Effects of the biochar on crop growth was demonstrated in a farmer’s field, and field experiments with wheat, turnip rape, faba bean, potato, and sugar beet were conducted in 2010. The application rates varied between 7.5 and 20 t ha-1. The trace element concentrations in the biochar sample provided by the producer were well within safety limits at the applications rates used. The concentration of water-extractable P in biochar ranged from 5 to 150 mg/kg, revealing high variability even within a batch. There was an indication of higher soil moisture content over the growing season when biochar was applied. The liming effect was lower than by CaCO3. Biochar seemed not to have any effect on the stability of air-dry soil aggregates, but a trend of improved wet aggregate stability by biochar was seen. In farmer’s field, the demonstrated effect of biochar on turnip rape was a 38 % increase in yield in a more fertile field parcel, and even a 69 % yield increase in the least fertile parcel. The replicated field plot experiments were arranged in fertile soils of good soil structure, in which biochar did not give yield increases in any of the crop plant species used in the tests. Both positive as well as negative impacts were indicated. However, application of biochar to damaged soils of low fertility seems promising. The application rates at the range of 10 to 20 ha-1 seem feasible. However, as we got indication of even yield reductions in fertile soils, we recommend that farmers start experimenting with care, and target the least productive parcels to gain experience. The variability of the properties of the biochar, even from the same producer and process, was large. Clearly, more research on production of biochar best suited for agricultural use, and further research on biochar as soil conditioner are needed. 3 Preface This report is a compilation of results of the first year’s field and laboratory testing of biochar as soil conditioner, initiated as BSAS Helsinki 2010 commitment. It includes results most of which are preliminary. Especially the field experiments require several years to check for natural variability in growing conditions between years. With this reservation in mind, we believe much new information and directions for further research is included, as biochar has not to this extent been studied in Finland before. We would like to thank Senior Vice President Anja Silvennoinen at UPM and Professor Esa Vakkilainen at LUT, for partnership in our BSAS Commitment. The Chair of JÄRKI project, Mr Ilkka Herlin facilitated the partnership in an important way. We thank Farmer Markus Eerola for enthusiasm and cooperation. Professors Pirjo Mäkelä, Eila Turtola and Markku Yli-Halla contributed in sharing their expertise and in designing the studies. Director of Research Dr. Susanna Muurinen, Director Paavo Kuisma and Senior Researcher Katja Anttila supervised the sugar beet and potato experiments. We are grateful to RAHA project for close cooperation. The participants of the 1st Biochar Seminar in Helsinki in spring 2010 created an enthusiastic and inspiring network which has been important for our work. Especially, cooperation with Preseco Oy, the provider of the biochar used in the experiments, was essential to our research. Honkjoki Oy was an important partner. Contribution from the Ministry of Agriculture and Forestry, which granted us research funding for AgriHiili project (2010-2012) is gratefully acknowledged. Helsinki 12 December 2010 Authors List of contents page Abstract 3 1. Introduction 5 2. Review of current knowledge 6 3. Aims of the study 8 4. Material and methods 8 5. Results 11 6. Discussion 17 7. Conclusion and recommendations 18 References 19 ht t p- l i n k s 20 4 1. Introduction Biochar is material produced via pyrolysis of biomass feedstocks. It is a mixture of char and ash, but it is mainly (70 - 95%) carbon (C) (Luostarinen et al. 2010). Charring has a long history, and in many cultures, primitive kilns are still used for making char for fuel. Relatively small volumes of char are being produced in Finland for barbecuing. Potential for production of significant amounts of biochar exist, as pyrolysis based technologies are being developed for energy industry and for production of wide variety of chemicals from forest feedstocks. In forestry, beneficial effect of ash and char on regrowth of forest after forest fire is well known. Application to agricultural soils has not been practiced in modern farming. However, the bio-char technique, application of char to farmland as soil conditioner is not a new concept. Certain dark earths in the Amazon basin ("terra preta do indio") contain large amounts of biochar (Sombroek et al. 2003, see also Lehman et al. 2006). These soils have been found to be exceptionally fertile, in comparison to soils in the region that do not contain biochar (Lehman et al. 2003). Internationally, biochar research in recent years has been intensified especially because of the potential biochar provides in carbon sequestration. According to Lehman et al. (2006) biochar as soil conditioner provides an opportunity to annually sequester over 10 % of the carbon emitted due to land use change over the industrial era. This potential is significantly higher than in strategies based on increasing organic carbon in soils, which is estimated to be 0.4 - 1.2 Gt per year (Lal 2004). Production of biofuels by pyrolysis can produce ca. 30 kg biochar per GJ of produced energy. The projected potential for sequestration is estimated to be 5 – 10 Gt C per year, which is equivalent or more than present global emissions from fossil fuel use (5.4 Gt per year) (Lehmann et al. 2006). Global average is 100 - 200 t carbon per hectare (ha) of agricultural land. In humid and cool regions the soil storage is significantly higher than in arid and hot regions (Lal 2004). In Finnish agricultural soils – excluding organic soils such as peat – typically contain 100 -150 t C per ha. Cycling of organic carbon from soils to atmosphere is fast in comparison to cycling of biochar, which decomposes only very slowly. The retention times has been estimated to at least hundreds, but more likely thousands of years (Lehmann 2007). Hence, biochar technology provides an opportunity to turn the agri-food sector even to an carbon negative industry. The three main criteria in assessing feasibility of biochar technology are effects on crop productivity and safety, economy, and environment. 5 Potential benefits include (Lehman et al. 2003, 2006, Lehmann & Joseph 2009, Milne et al. 2007, McHenry 2009): 1) carbon sequestration by the natural process of photosynthesis 2) reduction of N2O- ja CH4 --emissions from soils 3) net production of energy in form of bioenergy 4) increase in soil fertility and yields of agricultural crops 5) increase in microbial activity in the soil 6) improvement of water retention capacity in the soil 7) improvement of cation exchange capacity in the soil 8) improvement of durability of soil aggregates and reduction of erosion 9) reduction in need of fertilization 10) reduction of nutrient leaching In realizing the potential, pyrolysis technologies such as, for example gasification, need to be developed to meet the multiple and not necessarily parallel needs of production of energy, distillates, and biochar.